EP1137931A1 - Systeme de mesure de densite de charge volumique - Google Patents

Systeme de mesure de densite de charge volumique

Info

Publication number
EP1137931A1
EP1137931A1 EP99965113A EP99965113A EP1137931A1 EP 1137931 A1 EP1137931 A1 EP 1137931A1 EP 99965113 A EP99965113 A EP 99965113A EP 99965113 A EP99965113 A EP 99965113A EP 1137931 A1 EP1137931 A1 EP 1137931A1
Authority
EP
European Patent Office
Prior art keywords
sensor
circuit
signal
conductors
endpiece
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99965113A
Other languages
German (de)
English (en)
Inventor
John S. Sargent
Frank T. Sargent
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SARGENT, FRANK T.
SARGENT, JOHN S.
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP1137931A1 publication Critical patent/EP1137931A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/221—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance by investigating the dielectric properties
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/56—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using electric or magnetic effects
    • G01F1/64—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using electric or magnetic effects by measuring electrical currents passing through the fluid flow; measuring electrical potential generated by the fluid flow, e.g. by electrochemical, contact or friction effects
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/226—Construction of measuring vessels; Electrodes therefor

Definitions

  • the housing for the sensor can provide means for stabilizing the relative positions of the sensor components.
  • the housing can include a ribbed insert which supports and surrounds the tubular flow channels and the parallel plate conductors.
  • the ribs of the insert extend along a plane orthogonal to the axes of the flow channels, resisting expansion of the channels under temperature or pressure stresses and maintaining a constant distance between the conductors and the flow channels. Additional stability can be provided by filling the ribbed insert with an epoxy material after attachment of the flow channel and conductor plate assembly. Once set, the epoxy provides significantly increased pressure tolerance, so that the sensor can be used in high pressure and/or high flow rate conditions.
  • the epoxy can be selected to provide improved thermal insulation.
  • Temperature-compensation circuitry can be included to minimize drift in measurements arising from environmental and material temperature variations. The actual compensation is performed by the sensor microprocessor or other controller.
  • the material temperature can be measured by conducting the temperature to a thermistor or other appropriate temperature measuring device.
  • a thermistor is integrated into the button used for static discharge, taking advantage of the thermal conductivity of the electrically- conductive coating of the button.
  • the button is formed with a cavity in which the thermistor is sealed in place using a thermally-conductive epoxy or other thermally-conductive material.
  • thermally-conductive epoxy between the button and the circuitry to which it attaches to the sensor's circuit board, is a thermally-insulating epoxy or other seal which prevent the transfer of heat along any pathway but the thermistor's wires.
  • a single thermistor should provide the necessary data and can be included in either the inlet or outlet ports. However, multiple thermistors can be utilized, with one installed at each of any combination of ports if desired.
  • Figure 2 is a side elevational view of the sensor of Fig. 1 and a solenoid- operated valve connected to the opening at each end of the sensor;
  • Figure 3 is a sectional view taken on line 3-3 of Fig. 1 ;
  • Figure 4 is a sectional view taken on line 4-4 of Fig. 1;
  • Figure 5 is an enlargement of one end of the structure illustrated in Fig.
  • Figure 6 is an enlargement of one end of an alternative structure having the sensor of Fig. 1 and a conductive screen assembly, with the conductive screen assembly in section;
  • Figure 7 is a perspective view of an alternative sensor of a type suitable for static operation;
  • Figure 23 is a perspective view of an alternative sensor having a concentric tubular conductor arrangement
  • Figure 32 is a schematic circuit diagram of a sensor portion of an alternative capacitive sensing circuit having a temperature-compensation circuit and a circuit that reverses the polarity of the sensor conductors with respect to the ground potential of a sensor shield;
  • Figure 33 is a schematic circuit diagram of the instrument portion of the alternative capacitive sensing circuit;
  • Figure 38 is a block diagram of another alternative sensing system that includes a microprocessor and compensates for temperature effects and non- linearities;
  • Figure 39 is a block diagram of still another alternative sensing system that includes two probes or sensors for measuring flow velocity;
  • Figure 44 is a perspective view of another alternative sensor having a parallel plate-like conductor arrangement
  • Figure 46 is a sectional view taken on line 46-46 of Fig. 45;
  • Figure 47 is a sectional view taken on line 47-47 of Fig. 45;
  • Figure 48 is an end view of the sensor of Fig. 45;
  • Figure 49 is a perspective view of one side of the endpiece of the sensor of Fig. 44;
  • Figure 54 is an end view of the support structure of the embodiment of Figure 53;
  • Figure 55 is a perspective view of an endpiece for use in the embodiment of Figure 53; and Figure 56 is a cross-sectional view taken along line 56-56 of Figure 55.
  • the inner and outer conductors may be coatings of conductive material deposited on concentric tubes made of glass or other insulating material.
  • a fluid introduced into a chamber between two conductors and electrically insulated from the conductors by an insulating or dielectric material defines a capacitance.
  • additional chambers may be included concentrically with one another to increase the capacitance of the sensor.
  • solenoid-operated valve assemblies 58 and 60 seal openings 20 and 22, respectively, during operation.
  • Assemblies 58 and 60 include valve cylinders 62 and 64, respectively, that are coupled to the female-threaded ends of endpieces 18 and 20.
  • a male- threaded end of valve cylinder 62 is coupled to the female-threaded end of endpiece 18.
  • a male-threaded end of a solenoid 66 is in turn coupled to a female-threaded end of valve cylinder 62 opposite its male-threaded end.
  • an electric field (E- field) blocking adapter 84 may be coupled to sensor 10.
  • Endpieces 102 and 104 are female-threaded and couple to the male-threaded ends of the tubular portion of outer conductor 94. Endpiece 104 may be removed to fill chamber 100 with a fluid.
  • the central conductor 106 of a coaxial cable 108 is soldered or friction-fit inside a longitudinal bore in inner conductor 96.
  • the shield 110 of coaxial cable 108 is retained between a frusto-conical shoulder 112 in the opening in endpiece 102 through which cable 108 extends and a correspondingly frusto-conical projection 114 in the end of the tubular portion of outer conductor 94. Because shield 110, endpiece 102, and outer conductor 94 are all electrically conductive and in contact with one another, they are all at the same ground potential and provide shielding against external electric fields.
  • a third 555-type timer chip 144 configured as a free-running oscillator generates at its output (OUTPUT) a trigger signal 146 that has a frequency proportional to the value of a capacitor 148, the first terminal of which is coupled to the THRESHOLD and TRIGGER inputs.
  • the second terminal of capacitor 148 is connected to ground.
  • a resistor 150 is connected between the first terminal of capacitor 148 and the DISCHARGE input of timer chip 144.
  • the R-C time constant defined by capacitor 148 and resistor 150 thus determines the duty cycle of trigger signal 146.
  • Another resistor 152 is connected between the DISCHARGE input of timer chip 144 and the power supply voltage.
  • a capacitor 154 is connected between the CONTROL input of timer chip 144 and ground.
  • the RESET input is connected to the power supply voltage.
  • Trigger signal 146 is provided to the RESET inputs of timer chips 122 and 124.
  • 555-type timers are used in these embodiments because they are economical and readily available commercially. Nevertheless, other timer circuits may be used if higher frequency operation or extreme accuracy is desired. Furthermore, the free-running oscillators described above are preferred over alternative circuits such as one-shot circuits because the capacitance values of the sensor may be small, thereby degrading the signal if one-shots are used. Conventional timer chips, such as 555 timers, are more tolerant of small capacitance values when configured to operate as free-running oscillators than when configured to operate as one-shots. Although the operation of the circuit is described in further detail below, broadly stated, the circuit determines the frequency difference between test signal 130 and reference signal 134 by subtracting one signal from the other.
  • the output of AND gate 173 is provided to the clock (CLK) input of each of counter chips 164, 166, 168 and 170.
  • the outputs of counter chips 164, 166, 168 and 170 are provided to four binary-coded decimal (BCD)-to-seven segment decoder/drivers 172, 174, 176 and 178, each of which in turn drives one offour single-digit seven-segment displays 180, 182, 184 and 186.
  • a display latch signal 183 is generated by a flip-flop 181 (Fig. 12) in response to trigger signal 146 and provided to each of decoder/drivers 172, 174, 176 and 178.
  • the circuit further includes a clamping circuit that clamps difference signal 162 to a zero frequency when test signal 130 has a frequency greater than that of reference signal 134.
  • the circuit is preferably configured so that the display indicates a measurement of zero when test signal 130 has a frequency equal to that of reference signal 134.
  • the display indicates a higher measurement when test signal 130 has a frequency lower than that of reference signal 134.
  • the problem that the clamping circuit addresses is ensuring that the display indicates a measurement only when the sign of the frequency difference between the reference frequency and the test frequency is positive, i.e., when test signal 130 has a frequency lower than that of reference signal 134 from which it is subtracted. Absent the clamping circuit, when the frequencies of test signal 130 and reference signal 134 are close to one another, fluctuations that result in test signal 130 having a frequency higher than that of reference signal 134 would result in the display of an erroneous value.
  • flip-flop 200 In response to a high signal at the Q output of flip-flop 198, flip-flop 200 produces a low signal at its Q output on the next rising edge of test signal 130. Because the Q output is also coupled to the clear (CLR) input of flip-flop 198, flip-flop 198 is cleared in response to that rising edge. Thus, the output of flip- flop 200 in response to assertion of trigger signal 146 consists of exactly one cycle of test signal 130. Similarly, in response to a high signal at the Q output of flip-flop 202, flip-flop 204 produces a low signal at its Q output on the next rising edge of reference signal 134. Because the Q output is also coupled to the clear (CLR) input of flip-flop 202, flip-flop 202 is cleared in response to that rising edge. Thus, the output of flip-flop 204 in response to assertion of trigger signal 146 consists of exactly one cycle of reference signal 134.
  • the error indicator circuit includes a transistor 214, a resistor 216 and a capacitor 218 (Fig. 11).
  • the collector of transistor 214 is coupled to the supply voltage; the base is coupled to test signal 130; and the emitter is coupled to one terminal of resistor 216 and one terminal of capacitor 218.
  • the other terminals of resistor 216 and capacitor 218 are coupled to ground.
  • Test signal 130 charges capacitor 218.
  • Resistor 216 discharges capacitor 218 more slowly than test signal 130 charges it.
  • the voltage on capacitor 218 remains above the value corresponding to a high logic level (typically about 2.5 volts for chips having transistor-transistor logic (TTL), although CMOS or any other chip technology would be suitable).
  • TTL transistor-transistor logic
  • Flip-flop 156 produces difference signal 162, which has a frequency equal to the frequency difference between test signal 130 and reference signal 134.
  • a clamping circuit which includes two one-and-only-one circuits, ensures that flip-flop 156 responds only when the sign of difference signal 162 is positive, i.e., when test signal 130 has a frequency less than that of reference signal 134.
  • the clamping circuit clamps difference signal 162 to zero when test signal 130 has a frequency greater than that of reference signal 134.
  • the indicator circuit also includes cascaded counters 164, 166, 168 and 170 that produce a count in response to difference signal 162.
  • Trigger signal 146 periodically resets the count.
  • a digital display produces a numeric value corresponding to the count.
  • sensor electronics 344 including a digital display 346.
  • Display 346 has a window that fits within an opening in body 310 and thus allows a user to read the displayed value representing the measured quantity.
  • Electronics 344 may comprise any of the circuitry described above, or any of the alternative circuitry described below.
  • a multiple-pin connector 348 fits within an opening in body 310 and provides signals for external data acquisition devices or test equipment (not shown). As illustrated in Fig.21 , a sensor of the general type illustrated in Figs. 15-
  • the remaining portion of the circuit relate to providing error indications, as described above with respect to the embodiment illustrated in Fig. 33. If the measurement signal is stuck low, a circuit comprising a transistor 662, a resistor 664, a capacitor 666 and an inverter 668 cause the BMS pin of connector 574 to go high. If the measurement signal is stuck low, a circuit comprising an inverter 670, a transistor 672, a resistor 674, a capacitor 676 and another inverter 678 cause the BMK pin of connector 498 to go high.
  • Figure 35 illustrates still another alternative circuit.
  • the indicator is not a digital display but rather consists of two light-emitting diodes (LEDs) 680 and 682.
  • a 4046-type phase-locked loop chip 684 generates the difference signal.
  • the oscillator frequency of chip 684 is determined by two resistors 686 and 688 coupled between a designated pin (R1) and ground, and a capacitor 544 coupled between two designated pins (C).
  • Resistor 688 is a variable resistor that facilitates calibration.
  • the control pin (CONT) is coupled via a resistor 690 to the phase error ( ⁇ ) pin as well as coupled via a capacitor 692 to ground.
  • the output (OUT) and compare (COMP) pins are coupled together.
  • the measurement signal produced by the sensor is available at the connector 694, which is coupled to the signal (SIG) pin of chip 684.
  • the signal produced at the phase error pin represents the difference between the oscillator frequency of chip 684 and the frequency of the measurement signal produced by the sensor.
  • the phase error pin of chip 684 is also coupled to a circuit that controls
  • LEDs 680 and 682 comprising a transistor 696, a resistor 698, a capacitor 700, two inverters 702 and 704, two NOR gates 706 and 708, two transistors 710 and 712, and two resistors 714 and 716.
  • the difference signal produced at the phase error pin controls transistor 696.
  • the circuit turns one of LEDs 680 and 682 on and the other off. More specifically, when the difference signal has a frequency greater than a frequency determined by the time constant defined by resistor 698 and capacitor 700, transistor 696 is essentially maintained in a continuously "on" state.
  • transistor 696 When transistor 696 is on, it turns on transistor 712 via NOR gate 706. Transistor 712 in turn drives LED 682 via resistor 716.
  • button material should be inert and non-reactive relative to the material being measured since it will be in direct contact with the material.
  • Appropriate materials can include coatings of metals such as gold, nickel or platinum.
  • button 990 is stamped brass with a gold coating.
  • An O- ring 995 or other appropriate seal means can be placed or formed around button 990 to create a seal to prevent the escape of material through bore 988.
  • a non- conductive (both thermally and electrically) washer/plug 989 which fits closely within bore 966 is placed on top of button 990 to hold button 990 in place.
  • An open center in plug 989 allows wires to be fed through to be connected to PCB 978.
  • sensor 910 includes electronics on a printed circuit board 924 that are also enclosed within the shield defined by body 912 and endpieces 914 and 916.
  • sensor 910 may have a suitable indicator, such as a digital display or LED indicator, and may in addition or alternatively, have a cable that provides electrical connections between circuit board 924 and external circuitry, as in other embodiments described above.
  • An electrical connector 926 on circuit board 924 extends through body 912 for this purpose.
  • An important feature of this embodiment is that electrical connection between circuit board 924 and conductors 918 and 920 is made through two tabs 928 and 930 that are integrally formed with conductors 918 and 920, respectively.
  • FIG. 40 A compensation and calibration method that may be used with the electronic circuits described above is illustrated in Fig. 40. This method is performed prior to beginning measurement. For example, it may be performed at the time of manufacture of the system. Indeed, it may be performed prior to manufacture during an engineering phase in which the system is adapted for a specific use, such as measuring oil as opposed to measuring water. Steps 748, 750, 752 and 754 of the method relate to computing a compensation function to compensate for variation in environmental temperature or for non-linear sensor response. Steps 758, 760, 762 and 764 of the method relate to a two-point calibration method.
  • a material sample of known or predetermined volume charge density is placed in the sensor, which is connected to the circuit in the manner described above with respect to various sensor and circuit embodiments.
  • the output of the circuit which indicates a volume charge density, is recorded along with the known or predetermined volume charge density.
  • a compensation function for sensor non-linearity For example, in computing a compensation function for sensor non-linearity, temperature is held constant over all iterations. When all data points have been collected, the function is computed at step 754.
  • a suitable software tool such as MATHCAD may be used to compute the function by fitting a function to the data points.
  • the function once computed, may be implemented in the circuit using discrete components or may be programmed into a microprocessor, as described above with respect to Fig. 38.
  • the circuit is adjusted such that its indicator reads at the highest end of the scale, e.g., the predetermined concentration in units of PPM.
  • this adjustment may be performed by adjusting the gain or delay oscillators included in some of the exemplary circuits, or by adjusting other suitable components.
  • the system may be used to measure any suitable values, and is not limited to measuring dissolved solids concentrations (in PPM or similar units), as in the examples described above.
  • One novel use for the flow-through embodiments of the sensor is for measuring flow velocity. To measure concentrations, the material sample should have constant velocity with respect to the sensor measurement chamber, because a change in velocity produces a change in the measurement. Thus, to measure flow, the sensor need only be suitably calibrated.
  • the flowmeter includes two identical probes or sensors 774 and 776, two oscillator circuits 778 and 780, a subtractor circuit 782, a frequency counter circuit 784 and an indicator circuit 786.
  • Sensor 774 receives the fluid at a velocity to be measured.
  • Sensor 776 receives the fluid at a constant velocity. It may, for example, be immersed in the fluid at a zero velocity.
  • Oscillator circuit 778 produces a reference frequency in response to the impedance of sensor 774.
  • Oscillator circuit 780 produces a test frequency in response to the impedance of sensor 776.
  • subtractor circuit 782 produces a signal representing the difference of these frequencies and thus the measured value.
  • Frequency counter circuit 784 converts this frequency into a digital value and provides it to indicator circuit 786 for display.
  • the measurement process of the system of the present invention can be summarized with reference to Fig. 42.
  • the system comprising the sensor and circuit, measures a frequency in response to the sensor impedance, which reflects the volume charge density (and/or velocity) of the material sample within its measurement chamber.
  • the system compensates for environmental temperature by, for example, applying a suitable mathematic function to the measured frequency value.
  • the measured or test frequency is subtracted from a reference frequency.
  • a system incorporating the above-described sensors may be used for a variety of purposes, including measuring the extent of impurities in fluids, such as gases and water and other liquids, and measuring the flow rate of such fluids.
  • Application of such a system can range from, for example, a purified water handling system in an integrated circuit manufacturing facility to desalination plants to oil or gas pipeline monitoring.

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  • Chemical & Material Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Fluid Mechanics (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

L'invention porte sur un capteur capacitif qui inclut un ou plusieurs chambres à travers lesquelles une matière peut s'écouler. Deux conducteurs sont disposés de manière à entourer partiellement la chambre d'écoulement afin que la matière puisse s'écouler entre eux. Lorsque plus d'une chambre est utilisée, des conducteurs supplémentaires sont mis en place. Un circuit de mesure relié aux conducteurs produit une sortie correspondant à une différence entre une fréquence d'essai et une fréquence de référence. Un dispositif d'affichage affiche la capacité mesurée en tant que représentation proportionnelle à échelle continue ou représentation binaire. Ce système à capteur peut mesurer la densité de charge volumique d'un fluide ou des paramètres sensibles à des variations de densité de charge volumique, tels que la vitesse d'écoulement.
EP99965113A 1998-12-04 1999-12-03 Systeme de mesure de densite de charge volumique Withdrawn EP1137931A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
WOPCT/US98/25792 1998-12-04
PCT/US1998/025792 WO2000034794A1 (fr) 1998-12-04 1998-12-04 Systeme de mesure de la densite de charge volumique
PCT/US1999/028693 WO2000034767A1 (fr) 1998-12-04 1999-12-03 Systeme de mesure de densite de charge volumique

Publications (1)

Publication Number Publication Date
EP1137931A1 true EP1137931A1 (fr) 2001-10-04

Family

ID=22268426

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99965113A Withdrawn EP1137931A1 (fr) 1998-12-04 1999-12-03 Systeme de mesure de densite de charge volumique

Country Status (8)

Country Link
EP (1) EP1137931A1 (fr)
AU (2) AU1804599A (fr)
CA (1) CA2353457A1 (fr)
EG (1) EG22722A (fr)
MX (2) MXPA99006487A (fr)
TW (1) TW460694B (fr)
WO (2) WO2000034794A1 (fr)
ZA (1) ZA997357B (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6771074B2 (en) * 2002-01-31 2004-08-03 Eaton Corporation Probe assembly for a fluid condition monitor and method of making same
CA2678471A1 (fr) * 2007-03-02 2008-09-12 Bartec Gmbh Dispositif et procede de detection de quantite lors de la reception et/ou du prelevement d'un liquide contenant une fraction gazeuse
TWI449913B (zh) * 2011-03-10 2014-08-21 China Steel Corp Sintered Mineral Density Detection Device
TWI567333B (zh) * 2014-07-22 2017-01-21 江紅 簡易式日光燈具
CN106680382A (zh) * 2015-11-06 2017-05-17 中国船舶工业系统工程研究院 一种船舶进气脱盐检测采样方法

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US3988668A (en) * 1975-10-17 1976-10-26 Robertshaw Controls Company Antistatic capacitance probe
GB1578527A (en) * 1976-03-13 1980-11-05 Lucas Industries Ltd Apparatus for detecting water in oil
JPH01165457U (fr) * 1988-05-12 1989-11-20
US4971015A (en) * 1988-11-08 1990-11-20 General Motors Corporation Combustion engine with multi-fuel capability
US5017909A (en) * 1989-01-06 1991-05-21 Standex International Corporation Capacitive liquid level sensor
US5051921A (en) * 1989-11-30 1991-09-24 David Sarnoff Research Center, Inc. Method and apparatus for detecting liquid composition and actual liquid level
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US5546005A (en) * 1995-01-09 1996-08-13 Flowline Inc. Guarded capacitance probe and related measurement circuit

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Title
See references of WO0034767A1 *

Also Published As

Publication number Publication date
EG22722A (en) 2003-07-30
MXPA01005569A (es) 2003-07-14
WO2000034767A1 (fr) 2000-06-15
MXPA99006487A (es) 2004-08-31
WO2000034794A1 (fr) 2000-06-15
AU1804599A (en) 2000-06-26
AU3109800A (en) 2000-06-26
ZA997357B (en) 2000-06-01
TW460694B (en) 2001-10-21
CA2353457A1 (fr) 2000-06-15

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